Enable persistent connections for IbmDb2.

Usage example in global.php:
<?php
return array(
    'db' => array(
        'driver' => 'IbmDb2',
        'database' => '*LOCAL',
        'username' => 'GUIDO',
        'password' => 'GUIDO55',
        'persistent' => true,
        'driver_options' => array(
            'i5_naming' => DB2_I5_NAMING_ON,
            'i5_libl' => 'WSDATA QGPL'
        ),
        'platform_options' => array(
            'quote_identifiers' => false
        )
    ),
    
    'service_manager' => array(
        'factories' => array(
            'Zend\Db\Adapter\Adapter' =>
'Zend\Db\Adapter\AdapterServiceFactory'
        )
    )
);


Change-Id: I42ff3d52b2f112cefb828432c93eb409d42b2cad
Enable persistent connections for IBMi

'db' => array(
        'driver' => 'IbmDb2',
        'database' => '*LOCAL',
        'username' => 'USER',
        'password' => 'PASSWORD',
        'persistent' => true,
        'driver_options' => array(
            'i5_naming' => DB2_I5_NAMING_ON,
            'i5_libl' => 'SOMELIB QGPL'
        ),
        'platform_options' => array(
            'quote_identifiers' => false
        )
    ),

'persistent' accepts true/false, or can be left out

Change-Id: I8b42f83e7be794286fc5b23e8dc195bb22b23b66
Merge branch '10211301' of git://github.com/guidofaecke/zf2 into guidofaecke-10211301
Refactored IbmDb2\Connection to not use array, also not use dynamic func. call